Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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Effect of Relative Humidity, Disk Acceleration, and Rest Time on Tribocharge Build-up at a Slider-Disk Interface of HDD

HDD에서 상대습도, 디스크 가속도, 정지시간이 슬라이더-디스크 인터페이스의 마찰대전 발생에 미치는 영향

  • Hwang J. (Department of Mechanical Engineering, Yonsei University) ;
  • Lee D.Y. (Department of Mechanical Engineering, Yonsei University) ;
  • Lee J. (Digital Printing Division, Samsung Electronics) ;
  • Choa S.H. (Samsung Advanced Institute of Technology, MEMS Lab.)
  • 황정호 (연세대학교 기계공학과) ;
  • 이대영 (연세대학교 기계공학과) ;
  • 이재호 (삼성전자 디지털프린팅사업부) ;
  • 좌성훈 (삼성종합기술원 MEMS Lab.)
  • Published : 2006.04.01
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Abstract

In hard disk drives as the head to disk spacing continues to decrease to facilitate recording densities, slider disk interactions have become much more severe due to direct contact of head and disk surfaces in both start/stop and flying cases. The slider disk interaction in CSS (contact-start-stop) mode is an important source of particle generation and tribocharge build-up. The tribocharge build-up in the slider disk interface can cause ESD (electrostatic discharge) damage. In turn, ESD can cause severe melting damage to MR or GMR heads. The spindle speed of typical hard disk drives has increased in recent years from 5400 rpm to 15000 rpm and even higher speeds are anticipated in the near future. And the increasing disk velocity leads to increasing disk acceleration and this might affect the tribocharging phenomena of the slider/disk interface. We investigated the tribocurrent/voltage build-up generated in HDD, operating at increasing disk accelerations. In addition, we examined the effects with relative humidity conditions and rest time. We found that the tribocurrent/voltage was generated during pico-slider/disk interaction and its level was about $3\sim16pA$ and $0.1\sim0.3V$, respectively. Tribocurrent/voltage build-up was reduced with increasing disk acceleration. Higher humidity conditions $(75\sim80%)$ produced lower levels tribovoltage/current. Therefore, a higher tribocharge is expected at a lower disk acceleration and lower relative humidity condition. Rest time affected the charge build-up at the slider-disk interface. The degree of tribocharge build-up increased with increasing rest time.

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References

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